Protective effect of topically applied polypeptide from Chlamys farreri against ultraviolet radiation-induced chronic skin damage in guinea pig     

Chi Mingliang  Cao Pengli  Yu Guoying  Zhu Li  Wang Yuejun  Wang Chunbo 《中国海洋湖沼学报》2003,21(4):319-323

Polypeptide fromChlamys farreri (PCF), a topical polypeptide isolated fromChlamys farreri, was used in this experiment aimed to investigate the photoprotective effect of PCF against chronic skin damage induced by ultraviolet A (UVA) and ultraviolet B (UVB) radiation. The chronic ultraviolet-irradiated guinea pig model was established, and visible changes in the skin including wrinkling, sagging and erythema were observed. Malondialdehyde (MDA) and antioxidant enzymes including superoxide dismutase (SOD) and glutathione peroxidase (GSH-px) in the dorsal skin were determined using biochemical methods. The results showed: (1) PCF (5 % and 20%) could greatly protect the dorsal skin of guinea pig against wrinkling, sagging and erythema induced by UV radiation in a concentration-dependent manner. (2) PCF could reduce MDA formation in the dorsal skin caused by UV irradiation, while increasing the activities of SOD and GSH-px. (3) The differences among the PCF groups and UV model group were significant (P<0.05,P<0.01). These results indicated that topical application, of PCF provided broad solar UV spectrum photoprotection; and that the antioxidant property of PCF might play a role in photoprotection. Project No. 39970638 supported by the NSFC, and the Science and Technology Bureau of Qingdao (No. 2001-28-50).  相似文献   

The anomalous ultraviolet light curves and IUE spectra of β Lyrae revisited     

A. P. Linnell 《Monthly notices of the Royal Astronomical Society》2002,334(4):963-973

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A ROSAT WFC observation of SW UMa: the EUV behaviour of dwarf novae in superoutburst explained     

M.R. Burleigh  J.P. Pye  S.W. Poulton  K.B. Sohl  P.J. Wheatley  G.A. Wynn 《Monthly notices of the Royal Astronomical Society》2001,325(4):1458-1462

During re-processing and analysis of the entire ROSAT Wide Field Camera (WFC) pointed observations data base, we discovered a serendipitous, off-axis detection of the cataclysmic variable SW UMa at the onset of its 1997 October superoutburst. Although long outbursts in this SU UMa-type system are known to occur every ∼ 450 d, none had ever been previously observed in the extreme ultra-violet (EUV) by ROSAT . The WFC observations began just ≈13 hr after the optical rise was detected. With a peak count rate of ∼ 4.5 count s⁻¹ in the S1 filter, SW UMa was temporarily the third brightest object in the sky in this waveband. Over the next ≈19 hr the measured EUV flux dropped to < 2 count s⁻¹, while the optical brightness remained essentially static at m _v∼11 . Similar behaviour has also been recently reported in the EUV light curve of the related SU UMa-type binary OY Car during superoutburst, as reported by Mauche & Raymond. In contrast, U Gem-type dwarf novae show no such early EUV dip during normal outbursts. Therefore, this feature may be common in superoutbursts of SU UMa-like systems. We expand on ideas first put forward by Osaki and Mauche & Raymond and offer an explanation for this behaviour by examining the interplay between the thermal and tidal instabilities that affect the accretion discs in these systems.  相似文献   

The electron pressure in the outer atmosphere of ε Eri (K2 V)     

C. Jordan  S.A. Sim  A.D. McMurry  M. Aruvel 《Monthly notices of the Royal Astronomical Society》2001,326(1):303-312

Observations of ε Eri (K2 V) have been made with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope . The spectra obtained show a number of emission lines which can be used to determine, or place limits on, the electron density and pressure. Values of the electron pressure are required in order to make quantitative models of the transition region and inner corona from absolute line fluxes, and to constrain semi-empirical models of the chromosphere. Using line flux ratios in Si  iii and O  iv a mean electron pressure of P _e= N _e T _e=4.8×10¹⁵ cm⁻³ K is derived. This value is compatible with the lower and upper limits to P _e found from flux ratios in C  iii , O  v and Fe  xii . Some inconsistencies which may be because of small uncertainties in the atomic data used are discussed.  相似文献   

Observations of hydrogen deficient binary Upsilon sagittarii     

N. Kameswara Rao  V. R. Venugopal 《Journal of Astrophysics and Astronomy》1985,6(2):101-112

The absolute magnitudeM _v of the hydrogen deficient binary υ Sgr has been estimated as -4.8 ± 1.0 from the distribution of the interstellar reddening, polarization and interstellar lines of the surrounding stars. From the ANS observations obtained at the time of the secondary eclipse, it appears that the hotter secondary is surrounded by a disc with colours of a B8-B9 star. The λ 1550 CIv absorption line arising in the stellar wind does not show any change in strength during the secondary minimum. The upper limit to the mass-loss rate from the high temperature wind is estimated as ≤ 5 × 10^-7 M⊙ yr^-1 from the 2 cm and 6 cm radio observations. Based on observations obtained with the Astronomical Netherlands Satellite and VLA. The National Radio Astronomy Observatory’s Very Large Array at Socorro, New Mexico is operated by Associated Universities Inc. under contract with the National Science Foundation.  相似文献   

F stars, metallicity and the ages of red galaxies at z > 1     

L. A. Nolan  J. S. Dunlop  R. Jimenez  A. F. Heavens 《Monthly notices of the Royal Astronomical Society》2003,341(2):464-476

We explore whether the rest-frame near-ultraviolet spectral region, observable in high-redshift galaxies via optical spectroscopy, contains sufficient information to allow the degeneracy between age and metallicity to be lifted. We do this by first testing the ability of evolutionary synthesis models to reclaim the correct metallicity when fitted to the near-ultraviolet spectra of F stars of known (subsolar and supersolar) metallicity. F stars are of particular interest because the rest-frame near-ultraviolet spectra of the oldest known elliptical galaxies at   z > 1  appear to be dominated by F stars near to the main-sequence turn-off.
We find that, in the case of the F stars, where the Hubble Space Telescope ultraviolet spectra have a high signal-to-noise ratio, fitting models in which the metallicity is allowed to vary as a free parameter is rather successful at deriving the correct metallicity. As a result, the estimated turn-off ages of these stars yielded by model-fitting are well constrained. Encouraged by this we have fitted these same variable-metallicity models to the deep, optical spectra of the   z ≃ 1.5 mJy  radio galaxies 53W091 and 53W069 obtained with the Keck telescope. While the age and metallicity are not so easily constrained for these galaxies, we find that even when metallicity is allowed as a free parameter, the best estimates of their ages are still ≥3 Gyr, with ages younger than 2 Gyr now strongly excluded. Furthermore, we find that a search of the entire parameter space of metallicity and star formation history using MOPED leads to the same conclusion. Our results therefore continue to argue strongly against an Einstein–de Sitter universe, and favour a Λ-dominated universe in which star formation in at least these particular elliptical galaxies was completed somewhere in the redshift range   z = 3–5  .  相似文献   

FUSE and HST ultraviolet observations of the disc wind of RW Sextantis     

R. K. Prinja  K. S. Long  C. S. Froning  C. Knigge  D. K. Witherick  J. S. Clark  F. A. Ringwald 《Monthly notices of the Royal Astronomical Society》2003,340(2):551-561

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Simultaneous XMM–Newton and ESO VLT observations of supernova 1995N: probing the wind–ejecta interaction     

L. Zampieri  P. Mucciarelli  A. Pastorello  M. Turatto  E. Cappellaro  S. Benetti 《Monthly notices of the Royal Astronomical Society》2005,364(4):1419-1428

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紫外线照射剂量对九孔鲍胚胎及幼虫的影响     

严正凛  关瑞章  胡家财  陈晓凤 《台湾海峡》2007,26(3):404-409

采用不同的紫外线照射剂量的海水诱导九孔鲍产卵,观察其对卵子的受精率、畸形率和孵化率的影响.紫外线照射剂量的配制方法是:用紫外线照射过的最大剂量的海水与新鲜海水混合配制出各种剂量的海水.实验把雌亲鲍分成7组,每组20只,分别用紫外线照射剂量为0(对照组)、450、600、750、900、1 050和1 200mW.h/dm3的海水进行刺激产卵.试验重复3次.结果表明,紫外线照射剂量在1 200mW.h/dm3以内,对卵子的受精率影响不大;紫外线照射剂量在750mW.h/dm3以内,对卵子的畸形率影响不大,但在900~1 200mW.h/dm3,对卵子的畸形率影响很大;紫外线照射剂量在600mW.h/dm3以内,对卵子的孵化率没有什么影响,但在750~1 200mW.h/dm3,对卵子的孵化率影响很大.综合考虑卵子的受精率、畸形率和孵化率,九孔鲍催产的适宜的紫外线照射剂量应为450~750mW.h/dm3.  相似文献   

合浦珠母贝卵子电击脉冲参数的初步研究     

喻达辉  贾晓平  陈素文  李夏  朱嘉濠 《海洋科学》2005,29(8):15-19

运用电脉冲转基因仪对合浦珠母贝卵子进行电脉冲处理以优化电穿孔法转基因的电击参数。实验中调制百分比：100％；脉冲间隔：1．0s：电极距离：2mm；脉冲个数：5个，参数保持不变。用不同的电脉冲参数组合（脉冲电压100-400V、脉冲持续时间0．5～3．0ms、脉冲频率10～50kHz，共28个组合）对卵子电击，然后加入精子进行授精，统计各组受精率和孵化率，以受精率和孵化率达到50％以上为衡量指标。结果表明，合浦珠母贝卵子对低脉冲频率和高电压非常敏感，当频率低于20kHz或脉冲电压高于400V时对卵子损伤较大。脉冲持续时间对其影响不大，适应范围较宽。优化的转基因电击脉冲参教组合为：脉冲电压1.0kV／cm，脉冲持续时间20ms，脉冲频率50kHz，或者脉冲电压1．5kV／cm，脉冲持续时间1．5ms，脉冲频率50kHz。  相似文献